Methods of indentifying sweet taste modulators

• US 8,119,359 B2
• Filed: 01/28/2011
• Issued: 02/21/2012
• Est. Priority Date: 04/19/2001
• Status: Expired due to Term

• Current Assignee: Firmenich SA
• Original Assignee: Senomyx Inc
• Inventors: Adler, Jon E., Li, Xiaodong, Staszewski, Lena, Xu, Hong, Echeverri, Fernando
• Primary Examiner(s): LANDSMAN, ROBERT S
• Application Number:
  US13/016,887
• Publication Number:
  US 20110201046A1
• Time in Patent Office: 389 Days
• Field of Search: None
• US Class Current: 435/7.21
• CPC Class Codes: C07K 14/723 G protein coupled receptor, e.g. TSHR-thyrotropin-receptor, LH/hCG receptor, FSH receptor
• CPC Class Codes: G01N 2333/705 Assays involving receptors, cell surface antigens or cell surface determinants
• CPC Class Codes: G01N 2333/726 G protein coupled receptor, e.g. TSHR-thyrotropin-receptor, LH/hCG receptor, FSH
• CPC Class Codes: G01N 2500/00 Screening for compounds of potential therapeutic value
• CPC Class Codes: G01N 33/5008 for testing or evaluating the effect of chemical or biological compounds, e.g. drugs, cosmetics
• CPC Class Codes: G01N 33/5023 on expression patterns
• CPC Class Codes: G01N 33/5041 involving analysis of members of signalling pathways
• CPC Class Codes: G01N 33/74 involving hormones or other non-cytokine intercellular protein regulatory factors such as growth factors, including receptors to hormones and growth factors

Abstract

Newly identified mammalian taste-cell-specific G protein-coupled receptors which function as hetero-oligomeric complexes in the sweet taste transduction pathway, and the genes and cDNA encoding said receptors are described. Specifically, T1R G protein-coupled receptors active in sweet taste signaling as hetero-oligomeric complexes, and the genes and cDNA encoding the same, are described, along with methods for isolating such genes and for isolating and expressing such receptors. Methods for identifying putative taste modulating compounds using such hetero-oligomeric complexes also described, as is a novel surface expression facilitating peptide useful for targeting integral plasma membrane proteins to the surface of a cell.

Claims

1. A method of screening for a compound that putatively blocks or activates sweet taste signaling, the method comprising the steps of:

(a) contacting cells comprising isolated mammalian cells or cultured mammalian cells with one or more compounds, wherein said cells express a receptor that binds to sweet taste compounds; and

(b) detecting whether said one or more compounds specifically bind to said receptor and/or specifically activate said receptor and, based thereon, identifying said one or more compounds as compounds that putatively block or activate sweet taste signaling, wherein

(1) said receptor that binds to sweet compounds comprises a T1R2 polypeptide and a T1R3 polypeptide,

(2) said T1R2 polypeptide is selected from the group consisting of;

(i) a polypeptide that is identical to the polypeptide of SEQ ID NO;

4; and

(ii) a polypeptide that is at least 90% identical to the polypeptide of SEQ ID NO;

4; and

(3) said T1R3 polypeptide is selected from the group consisting of;

(i) a polypeptide that is identical to the polypeptide of SEQ ID NO;

6; and

(ii) a polypeptide that is at least 90% identical to the T1R3 polypeptide of SEQ ID NO;

6.

3. The method of claim 1 that further includes a taste test to determine the effect of said identified compound on sweet taste and, based on the result of the taste test, identifying the compound as a compound that blocks or activates sweet taste signaling.

5. The method of claim 1, wherein said T1R2 polypeptide is expressed from a gene that is endogenous to said cells, and wherein said T1R2 polypeptide is at least 95% identical to the polypeptide of SEQ ID NO:

4.

6. The method of claim 1, wherein said T1R3 polypeptide is expressed from a gene that is endogenous to said cells, and wherein said T1R3 polypeptide is at least 95% identical to the T1R3 polypeptide of SEQ ID NO:

6.

7. The method of claim 1, wherein said T1R2 polypeptide is expressed from a gene that is endogenous to said cells and T1R3 polypeptide is expressed from a gene that is endogenous to said cells, and wherein said T1R2 polypeptide is at least 95% identical to the polypeptide of SEQ ID NO:

4 and/or said T1R3 polypeptide is at least 95% identical to the T1R3 polypeptide of SEQ ID NO;

6.

11. The method of claim 1, wherein said cells include human cells.

13. The method of claim 5, wherein said cells include human cells.

14. The method of claim 6, wherein said cells include human cells.

15. The method of claim 7, wherein said cells include human cells.

19. The method of claim 1, wherein said cells are identified by a method comprising detecting the expression of a T1R2 and/or T1R3 polypeptide or T1R2- and/or T1R3-encoding nucleic acid by said cells.

21. The method of claim 5, wherein said cells are identified by a method comprising detecting the expression of a T1R2 and/or T1R3 polypeptide or T1R2- and/or T1R3-encoding nucleic acid by said cells.

22. The method of claim 6, wherein said cells are identified by a method comprising detecting the expression of a T1R2 and/or T1R3 polypeptide or T1R2- and/or T1R3-encoding nucleic acid by said cells.

23. The method of claim 7, wherein said cells are identified by a method comprising detecting the expression of a T1R2 and/or T1R3 polypeptide or T1R2- and/or T1R3-encoding nucleic acid by said cells.

27. The method of claim 1, wherein said cells comprise a heterologous nucleic acid encoding a detectable label that provides for the identification of compounds that specifically bind or modulate the activity of said receptor.

29. The method of claim 5, wherein said cells comprise a heterologous nucleic acid encoding a detectable label that provides for the identification of compounds that specifically bind or modulate the activity of said receptor.

30. The method of claim 6, wherein said cells comprise a heterologous nucleic acid encoding a detectable label that provides for the identification of compounds that specifically bind or modulate the activity of said receptor.

31. The method of claim 7, wherein said cells comprise a heterologous nucleic acid encoding a detectable label that provides for the identification of compounds that specifically bind or modulate the activity of said receptor.

35. The method of claim 19, wherein said cells comprise a heterologous nucleic acid encoding a detectable label that provides for the identification of compounds that specifically bind or modulate the activity of said receptor.

37. The method of claim 21, wherein said cells comprise a heterologous nucleic acid encoding a detectable label that provides for the identification of compounds that specifically bind or modulate the activity of said receptor.

38. The method of claim 22, wherein said cells comprise a heterologous nucleic acid encoding a detectable label that provides for the identification of compounds that specifically bind or modulate the activity of said receptor.

39. The method of claim 23, wherein said cells comprise a heterologous nucleic acid encoding a detectable label that provides for the identification of compounds that specifically bind or modulate the activity of said receptor.

43. The method of claim 1, wherein said cells endogenously expresses a G protein or comprise a heterologous nucleic acid encoding a G protein.

45. The method of claim 19, wherein said cells endogenously expresses a G protein or comprise a heterologous nucleic acid encoding a G protein.

47. The method of claim 43, wherein said G protein comprises Gα

15 or Gα

16 or another promiscuous G protein.

49. The method of claim 45, wherein said G protein comprises Gα

15 or Gα

16 or another promiscuous G protein.

51. The method of claim 1, wherein said cells are identified using at least one probe that specifically detects the expression of T1R2 and/or T1R3 genes by said cells.

53. The method of claim 5, wherein said cells are identified using at least one probe that specifically detects the expression of T1R2 and/or T1R3 genes by said cells.

54. The method of claim 6, wherein said cells are identified using at least one probe that specifically detects the expression of T1R2 and/or T1R3 genes by said cells.

55. The method of claim 7, wherein said cells are identified using at least one probe that specifically detects the expression of T1R2 and/or T1R3 genes by said cells.

59. The method of claim 51, wherein said at least one probe comprises a nucleic acid that specifically detects T1R2 or T1R3 nucleic acids expressed by said cells or comprises an antibody that specifically detects T1R2 or T1R3 polypeptides expressed by said cells.

61. The method of claim 53, wherein said at least one probe comprises a nucleic acid that specifically detects T1R2 or T1R3 nucleic acids expressed by said cells or comprises an antibody that specifically detects T1R2 or T1R3 polypeptides expressed by said cells.

62. The method of claim 54, wherein said at least one probe comprises a nucleic acid that specifically detects T1R2 or T1R3 nucleic acids expressed by said cells or comprises an antibody that specifically detects T1R2 or T1R3 polypeptides expressed by said cells.

63. The method of claim 55, wherein said at least one probe comprises a nucleic acid that specifically detects T1R2 or T1R3 nucleic acids expressed by said cells or comprises an antibody that specifically detects T1R2 or T1R3 polypeptides expressed by said cells.

67. The method of claim 59, wherein said T1R2 or T1R3 nucleic acid is an RNA and is detected by a method selected from the group consisting of Northern analysis, dot blot, RNase protection, S1 analysis, a nucleic acid amplification technique, and in situ hybridization.

69. The method of claim 61, wherein said T1R2 or T1R3 nucleic acid is an RNA and is detected by a method selected from the group consisting of Northern analysis, dot blot, RNase protection, S1 analysis, a nucleic acid amplification technique, and in situ hybridization.

70. The method of claim 62, wherein said T1R2 or T1R3 nucleic acid is an RNA and is detected by a method selected from the group consisting of Northern analysis, dot blot, RNase protection, S1 analysis, a nucleic acid amplification technique, and in situ hybridization.

71. The method of claim 63, wherein said T1R2 or T1R3 nucleic acid is an RNA and is detected by a method selected from the group consisting of Northern analysis, dot blot, RNase protection, S1 analysis, a nucleic acid amplification technique, and in situ hybridization.

75. The method of claim 67, wherein said at least one probe comprises a T1R2- and/or T1R3-specific primer.

77. The method of claim 67, wherein said at least one probe comprises a T1R2- and/or T1R3-specific primer.

78. The method of claim 70, wherein said at least one probe comprises a T1R2- and/or T1R3-specific primer.

79. The method of claim 71, wherein said at least one probe comprises a T1R2- and/or T1R3-specific primer.

83. The method of claim 1, wherein step (b) comprises detecting an alteration in said cells in one or more of intracellular Ca²⁺, intracellular IP3, an intracellular cyclic nucleotide, intracellular cAMP, intracellular cGMP, membrane voltage, and G protein binding to GTPγ

S.

85. The method of claim 5, wherein step (b) comprises detecting an alteration in said cells in one or more of intracellular Ca²⁺, intracellular IP3, an intracellular cyclic nucleotide, intracellular cAMP, intracellular cGMP, membrane voltage, and G protein binding to GTPγ

S.

86. The method of claim 6, wherein step (b) comprises detecting an alteration in said cells in one or more of intracellular Ca²⁺, intracellular IP3, an intracellular cyclic nucleotide, intracellular cAMP, intracellular cGMP, membrane voltage, and G protein binding to GTPγ

S.

87. The method of claim 7, wherein step (b) comprises detecting an alteration in said cells in one or more of intracellular Ca²⁺, intracellular IP3, an intracellular cyclic nucleotide, intracellular cAMP, intracellular cGMP, membrane voltage, and G protein binding to GTPγ

S.

91. The method of claim 1, wherein said cells are obtained from a mammalian tissue.

93. The method of claim 5, wherein said cells are obtained from a mammalian tissue.

94. The method of claim 6, wherein said cells are obtained from a mammalian tissue.

95. The method of claim 7, wherein said cells are obtained from a mammalian tissue.

99. The method of claim 1, wherein said cells are obtained from a human tissue.

101. The method of claim 5, wherein said cells are obtained from a human tissue.

102. The method of claim 6, wherein said cells are obtained from a human tissue.

103. The method of claim 7, wherein said cells are obtained from a human tissue.

107. The method of claim 1, wherein said cells are obtained from a human cell culture.

109. The method of claim 5, wherein said cells are obtained from a human cell culture.

110. The method of claim 6, wherein said cells are obtained from a human cell culture.

111. The method of claim 7, wherein said cells are obtained from a human cell culture.

115. The method of claim 91, wherein said mammalian tissue comprises tongue, oral cavity tissue, gastrointestinal epithelium, or epiglottis.

117. The method of claim 93, wherein said mammalian tissue comprises tongue, oral cavity tissue, gastrointestinal epithelium, or epiglottis.

118. The method of claim 94, wherein said mammalian tissue comprises tongue, oral cavity tissue, gastrointestinal epithelium, or epiglottis.

119. The method of claim 95, wherein said mammalian tissue comprises tongue, oral cavity tissue, gastrointestinal epithelium, or epiglottis.

123. The method of claim 99, wherein said human tissue comprises tongue, oral cavity tissue, gastrointestinal epithelium, or epiglottis.

125. The method of claim 101, wherein said human tissue comprises tongue, oral cavity tissue, gastrointestinal epithelium, or epiglottis.

126. The method of claim 102, wherein said human tissue comprises tongue, oral cavity tissue, gastrointestinal epithelium, or epiglottis.

127. The method of claim 103, wherein said human tissue comprises tongue, oral cavity tissue, gastrointestinal epithelium, or epiglottis.

131. The method of claim 1, wherein at least one of said T1R2 or T1R3 polypeptides is expressed from a nucleic acid heterologous to said cells.

133. The method of claim 5, wherein at least one of said T1R2 or T1R3 polypeptides is expressed from a nucleic acid heterologous to said cells.

134. The method of claim 6, wherein at least one of said T1R2 or T1R3 polypeptides is expressed from a nucleic acid heterologous to said cells.

137. The method of claim 1, wherein said compound that modulates sweet taste signaling is an activator, inhibitor, stimulator, enhancer, agonist, blocker, or antagonist of sweet taste signaling.

139. The method of claim 5, wherein said compound that modulates sweet taste signaling is an activator, inhibitor, stimulator, enhancer, agonist, blocker, or antagonist of sweet taste signaling.

140. The method of claim 6, wherein said compound that modulates sweet taste signaling is an activator, inhibitor, stimulator, enhancer, agonist, blocker, or antagonist of sweet taste signaling.

141. The method of claim 7, wherein said compound that modulates sweet taste signaling is an activator, inhibitor, stimulator, enhancer, agonist, blocker, or antagonist of sweet taste signaling.

2. A method of screening for a compound that putatively modulates sweet taste signaling, the method comprising the steps of:

(a) contacting cells comprising isolated mammalian cells or cultured mammalian cells with one or more compounds, wherein said cells express a receptor that binds to sweet taste compounds; and

(b) detecting whether said one or more compounds affect the binding of another compound to said receptor and/or modulate the activation of said receptor by another compound and, based thereon, identifying said one or more compounds as compounds that putatively modulate sweet taste signaling, wherein

(1) said receptor that binds to sweet compounds comprises a T1R2 polypeptide and a T1R3 polypeptide,

(2) said T1R2 polypeptide is selected from the group consisting of;

(i) a polypeptide that is identical to the polypeptide of SEQ ID NO;

4; and

(ii) a polypeptide that is at least 90% identical to the polypeptide of SEQ ID NO;

4; and

(3) said T1R3 polypeptide is selected from the group consisting of;

(i) a polypeptide that is identical to the polypeptide of SEQ ID NO;

6; and

(ii) a polypeptide that is at least 90% identical to the T1R3 polypeptide of SEQ ID NO;

6.

4. The method of claim 2 that further includes a taste test to determine the effect of said identified compound on sweet taste and, based on the result of the taste test, identifying the compound as a compound that modulates sweet taste signaling.

8. The method of claim 2, wherein said T1R2 polypeptide is expressed from a gene that is endogenous to said cells, and wherein said T1R2 polypeptide is at least 95% identical to the polypeptide of SEQ ID NO:

4.

9. The method of claim 2, wherein said T1R3 polypeptide is expressed from a gene that is endogenous to said cells, and wherein said T1R3 polypeptide is at least 95% identical to the T1R3 polypeptide of SEQ ID NO:

6.

10. The method of claim 2, wherein said T1R2 polypeptide is expressed from a gene that is endogenous to said cells and T1R3 polypeptide is expressed from a gene that is endogenous to said cells, and wherein said T1R2 polypeptide is at least 95% identical to the polypeptide of SEQ ID NO:

4 and/or said T1R3 polypeptide is at least 95% identical to the T1R3 polypeptide of SEQ ID NO;

6.

12. The method of claim 2, wherein said cells include human cells.

16. The method of claim 8, wherein said cells include human cells.

17. The method of claim 9, wherein said cells include human cells.

18. The method of claim 10, wherein said cells include human cells.

20. The method of claim 2, wherein said cells are identified by a method comprising detecting the expression of a T1R2 and/or T1R3 polypeptide or T1R2- and/or T1R3-encoding nucleic acid by said cells.

24. The method of claim 8, wherein said cells are identified by a method comprising detecting the expression of a T1R2 and/or T1R3 polypeptide or T1R2- and/or T1R3-encoding nucleic acid by said cells.

25. The method of claim 9, wherein said cells are identified by a method comprising detecting the expression of a T1R2 and/or T1R3 polypeptide or T1R2- and/or T1R3-encoding nucleic acid by said cells.

26. The method of claim 10, wherein said cells are identified by a method comprising detecting the expression of a T1R2 and/or T1R3 polypeptide or T1R2- and/or T1R3-encoding nucleic acid by said cells.

28. The method of claim 2, wherein said cells comprise a heterologous nucleic acid encoding a detectable label that provides for the identification of compounds that specifically bind or modulate the activity of said receptor.

32. The method of claim 8, wherein said cells comprise a heterologous nucleic acid encoding a detectable label that provides for the identification of compounds that specifically bind or modulate the activity of said receptor.

33. The method of claim 9, wherein said cells comprise a heterologous nucleic acid encoding a detectable label that provides for the identification of compounds that specifically bind or modulate the activity of said receptor.

34. The method of claim 10, wherein said cells comprise a heterologous nucleic acid encoding a detectable label that provides for the identification of compounds that specifically bind or modulate the activity of said receptor.

36. The method of claim 20, wherein said cells comprise a heterologous nucleic acid encoding a detectable label that provides for the identification of compounds that specifically bind or modulate the activity of said receptor.

40. The method of claim 24, wherein said cells comprise a heterologous nucleic acid encoding a detectable label that provides for the identification of compounds that specifically bind or modulate the activity of said receptor.

41. The method of claim 25, wherein said cells comprise a heterologous nucleic acid encoding a detectable label that provides for the identification of compounds that specifically bind or modulate the activity of said receptor.

42. The method of claim 26, wherein said cells comprise a heterologous nucleic acid encoding a detectable label that provides for the identification of compounds that specifically bind or modulate the activity of said receptor.

44. The method of claim 2, wherein said cells endogenously expresses a G protein or comprise a heterologous nucleic acid encoding a G protein.

46. The method of claim 20, wherein said cells endogenously expresses a G protein or comprise a heterologous nucleic acid encoding a G protein.

48. The method of claim 44, wherein said G protein comprises Gα

15 or Gα

16 or another promiscuous G protein.

50. The method of claim 46, wherein said G protein comprises Gα

15 or Gα

16 or another promiscuous G protein.

52. The method of claim 2, wherein said cells are identified using at least one probe that specifically detects the expression of T1R2 and/or T1R3 genes by said cells.

56. The method of claim 8, wherein said cells are identified using at least one probe that specifically detects the expression of T1R2 and/or T1R3 genes by said cells.

57. The method of claim 9, wherein said cells are identified using at least one probe that specifically detects the expression of T1R2 and/or T1R3 genes by said cells.

58. The method of claim 10, wherein said cells are identified using at least one probe that specifically detects the expression of T1R2 and/or T1R3 genes by said cells.

60. The method of claim 52, wherein said at least one probe comprises a nucleic acid that specifically detects T1R2 or T1R3 nucleic acids expressed by said cells or comprises an antibody that specifically detects T1R2 or T1R3 polypeptides expressed by said cells.

64. The method of claim 56, wherein said at least one probe comprises a nucleic acid that specifically detects T1R2 or T1R3 nucleic acids expressed by said cells or comprises an antibody that specifically detects T1R2 or T1R3 polypeptides expressed by said cells.

65. The method of claim 57, wherein said at least one probe comprises a nucleic acid that specifically detects T1R2 or T1R3 nucleic acids expressed by said cells or comprises an antibody that specifically detects T1R2 or T1R3 polypeptides expressed by said cells.

66. The method of claim 58, wherein said at least one probe comprises a nucleic acid that specifically detects T1R2 or T1R3 nucleic acids expressed by said cells or comprises an antibody that specifically detects T1R2 or T1R3 polypeptides expressed by said cells.

68. The method of claim 60, wherein said T1R2 or T1R3 nucleic acid is an RNA and is detected by a method selected from the group consisting of Northern analysis, dot blot, RNase protection, S1 analysis, a nucleic acid amplification technique, and in situ hybridization.

72. The method of claim 64, wherein said T1R2 or T1R3 nucleic acid is an RNA and is detected by a method selected from the group consisting of Northern analysis, dot blot, RNase protection, S1 analysis, a nucleic acid amplification technique, and in situ hybridization.

73. The method of claim 65, wherein said T1R2 or T1R3 nucleic acid is an RNA and is detected by a method selected from the group consisting of Northern analysis, dot blot, RNase protection, S1 analysis, a nucleic acid amplification technique, and in situ hybridization.

74. The method of claim 66, wherein said T1R2 or T1R3 nucleic acid is an RNA and is detected by a method selected from the group consisting of Northern analysis, dot blot, RNase protection, S1 analysis, a nucleic acid amplification technique, and in situ hybridization.

76. The method of claim 68, wherein said at least one probe comprises a T1R2- and/or T1R3-specific primer.

80. The method of claim 72, wherein said at least one probe comprises a T1R2- and/or T1R3-specific primer.

81. The method of claim 73, wherein said at least one probe comprises a T1R2- and/or T1R3-specific primer.

82. The method of claim 74, wherein said at least one probe comprises a T1R2- and/or T1R3-specific primer.

84. The method of claim 2, wherein step (b) comprises detecting an alteration in said cells in one or more of intracellular Ca²⁺, intracellular IP3, an intracellular cyclic nucleotide, intracellular cAMP, intracellular cGMP, membrane voltage, and G protein binding to GTPγ

S.

88. The method of claim 8, wherein step (b) comprises detecting an alteration in said cells in one or more of intracellular Ca²⁺, intracellular IP3, an intracellular cyclic nucleotide, intracellular cAMP, intracellular cGMP, membrane voltage, and G protein binding to GTPγ

S.

89. The method of claim 9, wherein step (b) comprises detecting an alteration in said cells in one or more of intracellular Ca²⁺, intracellular IP3, an intracellular cyclic nucleotide, intracellular cAMP, intracellular cGMP, membrane voltage, and G protein binding to GTPγ

S.

90. The method of claim 10, wherein step (b) comprises detecting an alteration in said cells in one or more of intracellular Ca²⁺, intracellular IP3, an intracellular cyclic nucleotide, intracellular cAMP, intracellular cGMP, membrane voltage, and G protein binding to GTPγ

S.

92. The method of claim 2, wherein said cells are obtained from a mammalian tissue.

96. The method of claim 8, wherein said cells are obtained from a mammalian tissue.

97. The method of claim 9, wherein said cells are obtained from a mammalian tissue.

98. The method of claim 10, wherein said cells are obtained from a mammalian tissue.

100. The method of claim 2, wherein said cells are obtained from a human tissue.

104. The method of claim 8, wherein said cells are obtained from a human tissue.

105. The method of claim 9, wherein said cells are obtained from a human tissue.

106. The method of claim 10, wherein said cells are obtained from a human tissue.

108. The method of claim 2, wherein said cells are obtained from a human cell culture.

112. The method of claim 8, wherein said cells are obtained from a human cell culture.

113. The method of claim 9, wherein said cells are obtained from a human cell culture.

114. The method of claim 10 wherein said cells are obtained from a human cell culture.

116. The method of claim 92, wherein said mammalian tissue comprises tongue, oral cavity tissue, gastrointestinal epithelium, or epiglottis.

120. The method of claim 96, wherein said mammalian tissue comprises tongue, oral cavity tissue, gastrointestinal epithelium, or epiglottis.

121. The method of claim 97, wherein said mammalian tissue comprises tongue, oral cavity tissue, gastrointestinal epithelium, or epiglottis.

122. The method of claim 98, wherein said mammalian tissue comprises tongue, oral cavity tissue, gastrointestinal epithelium, or epiglottis.

124. The method of claim 100, wherein said human tissue comprises tongue, oral cavity tissue, gastrointestinal epithelium, or epiglottis.

128. The method of claim 104, wherein said human tissue comprises tongue, oral cavity tissue, gastrointestinal epithelium, or epiglottis.

129. The method of claim 105, wherein said human tissue comprises tongue, oral cavity tissue, gastrointestinal epithelium, or epiglottis.

130. The method of claim 106, wherein said human tissue comprises tongue, oral cavity tissue, gastrointestinal epithelium, or epiglottis.

132. The method of claim 2, wherein at least one of said T1R2 or T1R3 polypeptides is expressed from a nucleic acid heterologous to said cells.

135. The method of claim 8, wherein at least one of said T1R2 or T1R3 polypeptides is expressed from a nucleic acid heterologous to said cells.

136. The method of claim 9, wherein at least one of said T1R2 or T1R3 polypeptides is expressed from a nucleic acid heterologous to said cells.

138. The method of claim 2, wherein said compound that modulates sweet taste signaling is an activator, inhibitor, stimulator, enhancer, agonist, blacker, or antagonist of sweet taste signaling.

142. The method of claim 8, wherein said compound that modulates sweet taste signaling is an activator, inhibitor, stimulator, enhancer, agonist, blocker, or antagonist of sweet taste signaling.

143. The method of claim 9, wherein said compound that modulates sweet taste signaling is an activator, inhibitor, stimulator, enhancer, agonist, blocker, or antagonist of sweet taste signaling.

144. The method of claim 10, wherein said compound that modulates sweet taste signaling is an activator, inhibitor, stimulator, enhancer, agonist, blocker, or antagonist of sweet taste signaling.